Hazardous Material Storage and Leak Mitigation System
A self-contained storage system for hazardous materials includes a containment envelope enclosing a storage tank containing hazardous materials and forming a containment space between the storage tank and containment envelope. Leaked material is detected by one or more sensors in the containment space and, depending on the concentration or time rate of change in concentration of the leaked material, alarms and corresponding mitigation measures are reversibly activated to remove leaked material from the containment space.
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The U.S. Government has certain rights to this invention pursuant to Contract Number W9113M-08-C-125 awarded by the U.S. Army Space & Missile Defense Command.
CROSS-REFERENCE TO RELATED APPLICATIONSNot Applicable
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to apparatus and methods for the mitigation of and warning against leaks of hazardous liquids and gasses.
2. Related Art
Methods and systems for storing hazardous materials are known. Some systems, such as described in U.S. Pat. No. 4,523,454 are limited to the detection and secondary containment of a leaked fuel such as gasoline. Other systems, exemplified by U.S. Pat. No. 6,578,639, inject a neutralizer directly into a breached fuel tank to chemically neutralize the flammability or other hazardous property of leaking fuel. US 2004/0080424 discloses a flammable gas detection system that detects a flammable gas in an enclosed space, such as a garage.
The existing systems for storing hazardous materials are not adequate for the safe storage and transport of hazardous materials in all circumstances. The storage of hypergolic propellants, especially hypergolic propellant systems comprising both fuel and oxidizer exemplifies the need for new storage and transportation systems. The present invention addresses the need for storage and transportation systems for a wide variety of hazardous materials including chemical, biological, and radiological hazards.
BRIEF DESCRIPTION OF THE INVENTIONIn one aspect, the present invention is a system and method for the storage, handling, and transportation of hazardous materials.
In another aspect, the present invention is a system and method for the safe storage, handling, and/or transportation of hypergolic propulsion systems.
In yet another aspect, the present invention is a system and method for mitigating a hazard created by the leakage of a hazardous material from a storage container and warning personnel of the leakage and its severity.
The present storage and leak mitigation system uses a containment envelope to isolate the stored material from the surrounding environment. One or more sensors detect the presence of material leaked from a storage tank into a containment space between the storage tank and the containment envelope. The containment space is in fluid communication with means for mitigating a leak of stored material. The sensor(s) can be set to reversibly activate one or more alarms and one or more means of leak mitigation based upon the concentration or time rate of change of concentration of material detected in the containment space. Mitigation may include recirculating a gas between the containment space and a scrubber and/or introducing a mitigating fluid into the containment space. The mitigating fluid can be removed to a waste storage container or recirculated between the containment space and a mitigating fluid supply.
The system is described using a number of embodiments as examples. While storage of ammonia and hypergolic propellants are used to illustrate various aspects of the invention, it is to be understood that the present invention may be used to contain and transport a wide variety of materials posing a wide variety of hazards, including corrosive, oxidation, flammable, toxic, and biological hazards.
As used herein, the term “to chemically neutralize” is to be understood as to render a hazardous chemical substantially less hazardous by a chemical reaction between the hazardous chemical and another chemical.
As used herein, a “hazardous” material is a material that poses a hazard, including one or more of toxicity, biological, corrosive, inflammability, and explosive hazards.
For some applications, direct contact between mitigating fluid and the hazardous material storage tank may not be desirable. A containment and mitigation system comprising a scrubber but no flush or spray nozzle is shown in
Some applications of the present invention may require the use of more than one mitigating fluid, possibly in combination with one or more scrubbers. These applications may also require the use of multiple sensors or a single sensor capable of detecting more than one hazardous material.
Parts or all of the containment and mitigation system can be configured for portability. If the storage tank(s) is small enough, the entire system may be made portable. Additionally, the storage tank(s) and containment envelope may be configured to be separable from the remainder of the system so that the control and mitigation systems can be transferred from one storage envelope to another. Embodiments of this type would include couplings allowing reversible, secure fluid connection between one or more scrubbers and/or mitigating fluid supplies and the containment space.
EXAMPLE 1The system shown in
The controller is programmed to activate three different levels of mitigation corresponding to three predetermined ammonia concentrations in the containment space. At a concentration of 10 ppm, the controller activates a fan in the scrubber system. At a concentration of 60 ppm, the controller activates a pump in the mitigating fluid supply system, which delivers mitigating fluid into the containment space through a spray nozzle. At a concentration of 90 ppm, the controller activates a pump in the mitigating fluid supply system, which delivers mitigating fluid into the containment space through a flush nozzle, which floods the containment space with mitigating fluid. Three audible and/or visual alarms may be correlated to sensor readings corresponding to each of the predetermined ammonia concentrations. Once a mitigation to an ammonia leak is activated, it may be reversed when the concentration of ammonia in the containment space is reduced below the predetermined value that triggered the mitigation.
The variable response of the containment system to increasing concentrations of hazardous material provides several advantages over the prior art. In this example, the time dependent measure of ammonia concentration allows an initial assessment of the severity of an ammonia leak. For slow leaks, the recirculation of air in the containment space through the absorption chamber mitigates the leak and informs personnel of the leak and need for storage tank repair and transfer of the ammonia to another storage tank. For more severe leaks, the containment system provides two additional levels of mitigation that provide initial containment and mitigation while warning personnel of the severity of the leak and possibly providing time for personnel to evacuate the area. The severity of the leak, as indicated by the concentration of or time rate of concentration of ammonia in the containment space, may be indicated using different alarm states indicated by different audible and/or visual alarm signals.
The containment and mitigation system described in this example is a sealed system in which no vapor escaping the storage tank escapes the system. In some embodiments, it may be desirable to allow gas or fluid containing neutralized hazardous material to escape the system.
EXAMPLE 2The system shown in
The control unit for this application preferably comprises a large touchscreen display and audible as well as visible alarms. In this example, the control unit is programmed to activate the scrubber when the MMH concentration in the containment space reaches 300 ppm. The predetermined concentration, however, may be set to any selected value. Because hydrazine is a highly reactive chemical, the gas in the containment space of this embodiment is preferably a chemically inert gas such as nitrogen or argon. The gas may optionally be recirculated within the containment space using a fan or other means (not shown) to distribute leaked MMH to ensure rapid contacting of leaked MMH with the senor.
EXAMPLE 3The system shown in
For the embodiments described in examples 2 and 3, the activation of alarms and scrubbers is reversible such that, when the concentration of the hazardous gas in the containment space is reduced to a second predetermined value that is equal to or less than the first predetermined concentration, mitigation and, optionally, alarm activation is stopped.
EXAMPLE 4The system shown in
Claims
1. A system for storing a hazardous material comprising:
- a sealed storage tank containing the hazardous material,
- a containment envelope containing the storage tank and forming a containment space between the storage tank and the containment envelope,
- a sensor configured to detect the concentration of hazardous material in the containment space,
- a supply of mitigating fluid that sequesters or chemically neutralizes the hazardous material,
- a pump configured to deliver mitigating fluid to the containment space, and
- a controller in communication with the sensor and the pump
- wherein:
- the containment envelope comprises: a spray nozzle and a flush nozzle in fluid communication with the supply of mitigating fluid and a drain configured to allow mitigating fluid to exit the containment space and into a waste container or recirculation system and
- the controller is configured to deliver mitigating fluid to the spray nozzle when the sensor detects a first predetermined concentration of hazardous material in the containment space and to deliver mitigating fluid to the flush nozzle when the sensor detects a second predetermined concentration of hazardous material in the containment space.
2. The system of claim 1, further comprising:
- A scrubber comprising a material capable of sequestering or chemically neutralizing the hazardous material and in fluid contact with the containment space,
- means for recirculating gas between the containment space and the scrubber, and wherein
- the controller is configured to activate the means for recirculating gas between the containment space and the scrubber when the sensor detects a third predetermined concentration of hazardous material in the containment space.
3. The system of claim 1, wherein the controller is configured to deactivate the delivery mitigating fluid to the containment space when the concentration of hazardous material in the containment space falls below a predetermined value.
4. The system of claim 1, further comprising audible and visible alarms in communication with the controller.
5. The system of claim 1, wherein the hazardous material is a liquid or a compressed or liquefied gas.
6. The system of claim 1, wherein:
- the storage tank is a first storage tank containing a first hazardous material and further comprising:
- a second storage tank containing a second hazardous material, one or more sensors configured to detect the concentrations of the second hazardous material, a second supply of a second mitigating fluid and wherein:
- the controller is configured to: deliver first mitigating fluid to the spray nozzle when the sensor detects a first predetermined concentration of the first hazardous material in the containment space; deliver first mitigating fluid to the flush nozzle when the sensor detects a second predetermined concentration of the first hazardous material in the containment space; deliver second mitigating fluid to the spray nozzle when the sensor detects a first predetermined concentration of the second hazardous material in the containment space; and deliver second mitigating fluid to the flush nozzle when the sensor detects a second predetermined concentration of the second hazardous material in the containment space.
7. The system of claim 6, wherein:
- the first and second hazardous materials combine to form one or more products that are more toxic than the first and second hazardous materials or
- the first and second hazardous materials, when combined, form a flammable or explosive mixture.
8. A system for storing a hazardous material comprising:
- a sealed storage tank containing the hazardous material,
- a containment envelope containing the storage tank and forming a containment space between the storage tank and the containment envelope,
- a sensor configured to detect the concentration of hazardous material in the containment space,
- an alarm,
- a scrubber comprising a material capable of sequestering or chemically neutralizing the hazardous material and in fluid contact with the containment space,
- means for recirculating gas between the containment space and the scrubber, and
- a controller in communication with the sensor, the alarm, and the means for recirculating gas through the scrubber
- wherein:
- the controller is configured to activate an alarm and means for recirculating gas between the containment space and the scrubber when the sensor detects a first predetermined concentration of hazardous material in the containment space and to deactivate means for recirculating gas between the containment space and the scrubber when the sensor detects a second predetermined concentration of hazardous material in the containment space and
- the second predetermined concentration of hazardous material is less than or equal to the first predetermined concentration of hazardous material.
9. The system of claim 8, wherein the means for recirculation of gas between the containment space and the scrubber comprises a fan or a blower.
10. The system of claim 8, wherein the scrubber is selected from an eductor-style scrubber, a one-stage counter-current scrubber, a two-stage counter-current scrubber, and a cross-current packed bed chemical scrubber.
11. The system of claim 8, wherein the scrubber comprises a mitigating fluid supply.
12. The system of claim 8, wherein the storage tank is a first storage tank containing a first hazardous material and further comprising a second storage tank containing a second hazardous material, a second scrubber, and a second means for recirculating gas between the containment space and the second scrubber and wherein:
- the controller is further configured to activate an alarm and means for recirculating gas between the containment space and the second scrubber when the sensor detects a first predetermined concentration of the second hazardous material in the containment space and to deactivate means for recirculating gas between the containment space and the second scrubber when the sensor detects a second predetermined concentration of the second hazardous material in the containment space and
- the second predetermined concentration of the second hazardous material is less than or equal to the first predetermined concentration of the second hazardous material.
13. The system of claim 12, wherein the first hazardous material is hydrazine or monomethylhydrazine and the second hazardous material is a mixed oxide of nitrogen.
14. The system of claim 13, wherein:
- the first scrubber comprises a chemical neutralizer selected from the group consisting of ozone, a salt of hypochlorite, a salt of citric acid, and an aqueous solution comprising ozone, hypochlorite ion, hydrogen peroxide, and citric acid and
- the second scrubber comprises an aqueous solution comprising hydroxide, bicarbonate, or carbonate or a salt of hydroxide, bicarbonate, or carbonate.
15. The system of claim 8, wherein the gas recirculating between the containment space and the scrubber is a chemically inert gas.
16. The system of claim 8, further comprising:
- a supply of mitigating fluid that sequesters or chemically neutralizes the hazardous material,
- a pump configured to deliver mitigating fluid to the containment space, and wherein:
- the containment envelope comprises: a spray nozzle and a flush nozzle in fluid communication with the supply of mitigating fluid and a drain configured to allow mitigating fluid to exit the containment space and into a waste container or recirculation system;
- the controller is in communication with the pump, and
- the controller is configured to deliver mitigating fluid to the spray nozzle when the sensor detects a third predetermined concentration of hazardous material in the containment space and to deliver mitigating fluid to the flush nozzle when the sensor detects a fourth predetermined concentration of hazardous material in the containment space.
17. A method for storing tanks containing hazardous material comprising the steps of:
- enclosing the storage tank in a containment envelope, thereby creating a containment space between the storage tank and the containment envelope;
- measuring the concentration of hazardous material in the space;
- activating a means for removing hazardous material from the containment space when the concentration of hazardous material reaches a first predetermined concentration; and
- deactivating the means for removing hazardous material from the containment space when the concentration of hazardous material reaches a second predetermined concentration that is less than or equal to the first predetermined concentration.
18. The method of claim 17 further comprising the step of activating an alarm when the concentration of hazardous material in the containment space reaches one or both of the first and second predetermined concentrations.
19. The method of claim 17 wherein removing hazardous material from the containment space comprises spraying a mitigating liquid into the containment space and removing the mitigating liquid.
20. The method of claim 17 wherein removing hazardous material from the containment space comprises recirculating a gas between the containment space and a scrubber comprising a material that absorbs or chemically neutralizes the hazardous material.
Type: Application
Filed: Dec 10, 2008
Publication Date: Jun 10, 2010
Patent Grant number: 8357304
Applicant: Streamline Automation, LLC (Huntsville, AL)
Inventors: Alton Reich (Huntsville, AL), Roberto DiSalvo (Madison, AL), Stephen Doherty (New Hope, AL), H. Waite Dykes (Huntsville, AL)
Application Number: 12/331,715
International Classification: B09B 1/00 (20060101);